Unexpectedly efficient CO2 hydrogenation to higher hydrocarbons over non-doped Fe2O3

Since CO2 hydrogenation into higher hydrocarbons is an attractive approach to mitigate greenhouse effect and to reduce reliance on fossil feedstock, this reaction has been intensively studied over Fe based catalysts. They had, however, to be promoted with oxides of e.g. K, Cu, Mn and/or Ce to reduce undesired CH4 formation and to increase olefin selectivity. Here, we demonstrate, for the first time, that similar improvements can be achieved without using dopants but by preparing bare Fe2O3 according to a template-assisted synthesis method. Under optimized reaction conditions (total pressure of 15 bar, 623 K and H-2/CO2 =3/1), the selectivity to C-2-C-4 hydrocarbons with the olefin to paraffin ratio of 2.7 was about 37% at CO2 conversion of 40%, while the selectivity to C5+ hydrocarbons, CH4 and CO was around 36,12 and 15% respectively. Our thorough characterization study with complementary techniques (H-2-TPR, XRD, and Mossbauer spectroscopy) enabled us to conclude that this preparation method affects reducibility of Fe2O3 and, thus, its ability for in situ transformation into catalytically active iron carbide(s) under CO2-hydrogenation conditions. (C) 2016 Elsevier B.V. All rights reserved.